I have a '12 6.7 PSD that has ~ 46k miles and it's by far the best truck I've owned to date. Fuel economy ranges from 16.4 - 20 mpg consisting of city and Hwy driving (non towing).
To date I've replaced the wipers, shocks and just put on a new set of tires last month. Interior wise the leather seats are holding up really good and no rattles anywhere.